Several processes for the production of polyurethanes with high tear strength and softness and the polyurethanes themselves are known in the prior art. Among these are the following.
U.S. Pat. Nos. 4,054,556 and 4,039,514 disclose polyurethane/polyurea compositions comprising the reaction products of an organic diisocyanate, a glycol having a molecular weight of 500-5000 and a derivative of 2,4-diaminobenzoic acid selected from C.sub.1 -C.sub.8 alkyl and substituted alkyl esters, amides, alkyl substituted amides, anilides, substituted anilides, nitriles and mixtures thereof.
U.S. Pat. No. 4,587,275 discloses polyurethane urea elastomers produced by reacting polyisocyanates with compounds containing at least two isocyanate reactive hydrogen atoms having a molecular weight of 400-10,000 and mononuclear or dinuclear aromatic diamines. These aromatic diamines must have at least one sulfonamide group as a substituent on at least one of their aromatic rings. Known chain lengthening agents, activators, blowing agents, auxiliary agents and additives may also be included in the reaction mixture. Polyurethane elastomers produced by this process have excellent mechanical properties, especially, being soft yet highly tear resistant.
U.S. Pat. No. 4,254,272 discloses substituted aromatic diamines and polyurethantes cured thereby. The diamines are selected from 3,5-diamino4-tert-alkylbenzoates, 3,5-diamino-4-tert-alkylbenzonitriles and alkylene bis(3-amino-4-tert-alkylbenzoate).
U.S. Pat. No. 4,365,051 discloses a polyurethane cured by a diamine selected from cyclohexyl or phenyl 3,5-diamino-4-tert-alkylbenzoates, 3,5-diamino-4-tert-(C.sub.4 -C.sub.6 alkyl)-benzonitriles and alkylene bis(3-amino-4-tert-alkylbenzoate).
U.S. Pat. No. 3,681,290 discloses the preparation of polyurethanes cured by aromatic diamine containing ester groups wherein the amino groups are in the meta and/or para position(s) relative to the ester group, and with a substituent in the ortho position to at least one amino group.
U.S. Pat. No. 3,794,621 discloses polyurethane elastomers and a method for preparing them, wherein the polyurethane elastomers have structural units of the formula: ##STR1##